Compounded oil



Patented May 14, 1946 comoimnnn OIL George H. Denison, Jr., Oakland, and Paul C; Condit, Berkeley, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware i No Drawing. Application October 16, 1944, Serial No. 558,960

15 Claims.

This invention relates to lubricating oils and the like.

Salts of carbamic acids, that is, compounds of the generic formula 1 N-CXlXaM R: wherein R1 and R2 are organic radicals or hydro: gen, X1 and X: are oxygen or sulfur and M is a basic organic radical or a metal, have been proposed as lubricant additives for various purposes; e. g., as extreme pressure agents (Busse, U. S. Patent No. 2,201,258) as corrosion inhibitors (Loane, U. S. Patent No. 2,160,881) and as antioxidants (Faust, U. S, Patent No. 2,160,851). Matheson, U. S. Patent No. 2,265,851, suggests the use of metal salts of dialkyl, diaryl and other similar dithiocarbamic acids as motor oil detergents while Miller and Rutherford, in U. S. patent application Serial No. 441,964, filed May 6, 1942 now U. S. Patent No. 2,363,012, issued November 21, 1944, have shown that polyvalent metal dithiccarbamates derived from reduced cyclic petroleum nitrogen bases are a superior class of lubricant additives. Thus the p olyvalent metal petroleum base dithiocarbamates of Miller and Rutherford are oil-soluble and water-insoluble and function as superior antioxidants, corrosion inhibitors and detergents in motor oils.

This invention is concerned with the use 'in lubricating oils and the like, more particularly in crankcase lubricating oils, of salts of thiocarbamic acids; that is, this invention is concerned with the use in lubricating oils and the like of salts having the type formula wherein Ri-and R: are organic radicals or hydro gen (at least one It being an organic radical), Xi and X: are oxygen or sulfur (at least one X eing sulfur) and M is a salt-forming ion or radical.

This invention is particularly concerned with mineral oil lubricants. such as crankcase lubricants, compounded with small amounts of polyvalentmetal dithiocarbamat'es ha ving the type wherein both R1 and R2 are groups of hydrocarbon structure or together constitute a single bivalent radical of hydrocarbon structure; and M e is a'polyvalent metal the valences of which, other than that shown, are satisfied by the same or 5 different acid radicals or by hydroxyl radicals.

We have discovered that the performance and stability ,of a lubricating oil or the like is greatly and surprisingly improved by incorporating therein both a salt of a thiocarbamic acid and an aliphatic selenide.

The term "aliphatic selenide as used herein .is inclusive of. the monoselenidas or seleno ethers C.Sc-O

wherein the carbon atoms shown are aliphatic carbon atoms, and of the polyselenides carbon atoms and m is a small whole number, usually 1, 2 or 3. I a

' The composition of the invention comprises, therefore, (1) a base oil, usually constituting 90 per cent or more of the total composition although in greases it may constitute a smaller proportion, (2) a thiocarbamate and (3) a selenide These components will now be described in moreidetail. The base oil will usually be a petroleunioi1 of lubricating viscosity. It may range in viscosity from spindle Oils to cylinder stocks; it" may be from a paraflinic, naphthenic or mixed base crude petroleum; it may be refined by any one or several of various methods; and it may be a distillate consist in whole or in art of other oils, such as certain vegetable oils (e. g., castor oil, sperm oil), polymerized oleflns, oils synthesized from coal or oxides of carbon, amyl naphthalene. etc.

The thiocarbemates may be represented generically by theformula R1 Xi wherein R1 and R: are hydrogen or organic radicals, at least one B being an organic radical, X: and X: are oxygen or sulfur, at least one 2! being sulfur, and M is a basic nitrogenous radical or a metal. Where M is a polyvalent metal, it will be understood that other valences of the metal than that shown will be satisfied, by the same or different acid radicals or by an hydroxyl radical.

The preferred thiocarbamates arethe polyvawherein' the carbon atoms shown are aliphatic or residual oil, etc. However, the base oil may lent metal dithiocarbamates in which R1 and R2 are both hydrocarbon or substituted hydrocarbon groups which are sufficiently large (e. g., 4 to 20 carbon atoms each) to impart oil solubility tov the dithiocarbamate, or in which Ri-and R2 are a single bivalent hydrocarbon group as in the petroleum base dithiocarbamates discussed hereinbelow. The preferred polyvalent metals are zinc and cadmium. Among other metals that may be used are lithium, sodium,.potassium, magnesium, calcium, strontium, barium, aluminum, tin and lead.

The dithiocarbamates may be looked upon as derivatives of amines and carbon disulfide, since the usual method of preparing them is by reacting an amine with carbon disulfide and caustic alkali:

Rx Bl N-CSSK 1120 2 The various polyvalent metal salts may be prepared from the alkali metal salt by double decomposition. The preferred dithiocarbamates may, therefore, be regarded as polyvalent metal dithiocarbamates derived from secondary amines and containing sufficiently large hydrocarbon group or groups to render the salts oil-soluble. The secondary amine of which the salt is a derivative may be an aliphatic amine (di-alkyl, di-cycloalkyl, mixed alkyl-cycloalkyl, etc), an aromatic amine or a mixed aliphatic-aromatic amine and it may be an amine such as piperidine or its homologues in which the secondary nitrogen atom is part of a heterocyclic ring.

Illustrative examples or thiocarbamates that may be used in accordance with the invention are calcium, lead, zinc and cadmium dibutyl dithiocarbamates; zinc methyl cetyl dithiocarbamate; zinc dicetyl dithiocarbamate; zinc diamyl thiolcarbamate; zinc diamyl thionocarbamate; zinc monocetyl dithiocarbamate; zinc butyl amylpentamethylene .dithiocarbamate.

General methods of preparing thiocarbamates are available in the literature. The best method presently available for preparing dithiocarbambamates, which are of two types: thiolcarbamates,

are available in the literature; e. g., thiolcarbamates from amines and COS.

The preparation of "petroleum base" dithiocarbamates is described in detail in said Miller and Rutherford U. S. Patent No. 2,363,012. Briefly stated, the "petroleum base dithiocarbamates are prepared by extracting the nitrogen bases from nitrogen-containing cracked naphtha or the like, reducing the bases and reacting the reduced bases with carbon disulfideand caustic alkali to produce the alkali metal "petroleum base" dithiocarbamates, from which the polyvalent metal petroleum base dithiocarbamates can be prepared by double decomposition.

From the properties and reactions of the reduced, cracked petroleum nitrogen bases from which the aforesaid "petroleum base dithiocarbamates are derived, it is believed that the reduced bases are complex mixtures predominating A stituents, 0n the carbon portion of the ring. The

wherein M is a metal and one or more of the hydrogen atoms are substituted by short alkyl' groups (about C1 to C5) and/or by a condensed benzene ring.

Although the petroleum base" dithiocarbamates are principally piperidine and tetrahydroates is that method in which a primary or sec- I ondary amine is allowed to react with carbon disulfide and aqueous or alcoholic caustic soda or caustic potash, producing an alkali metal dithiocarbamate. This may be recovered by crystallization, but since the polyvalent metal salts are preferred, it will be the usual practice to add an aqueous solution of a water-soluble polyvalent metal salt, such as calcium chloride or zinc sulfate, to the reaction mixture (diluted with water if necessary) containing the alkali metal dithiocarbamate, thereby precipitating the desired polyvalent metal dithiocarbamate. This may be purified by crystallization from a suitable solvent, such as a light hydrocarbon thinner. Alternatively, to an aqueous solution of an alkali metal dithiocarbamate may be added petroleum thinner and to the mixture may-be added an aqueous solution of a polyvalent metal salt, thus quinoline derivatives, with one or more hydrocarbon substituents on the carbon part of the ring, dithiocarbamates derived from other ring type amines, such as trimethylene imine, tetramethylene imine and hexamethylene imine, preferably containing one part or more alkyl substituents on the carbon part of the ring, may also be used according to the invention.

The selenides, which form the. third component of the composition of the invention, may be represented as compounds having in the molecule the structure wherein the carbon atoms shown are aliphatic carbon atoms and m is a whole number, usually not greater than 3. The organic groups attached to the selenium group, -(Se)m, may be like or unlike groups and they may be straight or branched open chain or cyclic aliphatic groups; they may be saturated or unsaturated; and they may be substituted or unsubstituted, as by aromatic groups and by polar groups, such as halogen, amino, hydroxy, etc.

The preferred selenides are the primary monoselenides or primary seleno ethers, that is, compounds having th'e group -CH2SeCH;, and

which contain at least four carbon atoms'in each of the aliphatic radicals; or better yet, at least eight carbon atoms in each of the aliphatic radicals. a

Examples of selenldes that may be used in accordance with the invention are as follows: dipropyl, dibutyl, diamyl, dih'exyl, .dioctyl, decyl methyl, didecyl, diundecyl, dilauryl, ditetradecyl, cetyl ethyl, cetyl decyl, dicetyl, diheptadecyl, dieicosyl, di-paraflin, dibenzyl, bis (fl-chlorocetyl) and bis (p-hydroxy-cetyl) monoselenides (seleno ethers); dioctyl, didecyl, dil'auryl, dicetyl, diheptadecyl and di-eicosyl diselenides; the various monoand poly -selenides prepared by condensing sodium or other alkali metal monoor polyselenides with halogenated, e. g., chlorinated hydrocarbons, such as decyl chloride, dodecyl chloride, tetradecyl chloride, cetyl chloride, heptadecyl chloride, eicosyl chloride, chlorinated lubricating oil and chlorinated parailin wax. By "diparailin" selenides we mean selenides (monoand polyselenides) ofithe character of those produced by condensing chlorinated paramn wax with the appropriate alkali metal selenide, e. g., sodium selenide.

Suitable methods of preparing the aliphatic selenides are as follows:

(1) From aliphatic halides and a metal selenide or polyselenide, by condensation or metathesis in an inert solvent such as ethyl alcohol. This method is particularly suitable for the preparation of pure, simple selenides such. as dicetyl selenide, and for the preparation of mixtures of selenides, as from chlorinated wax..

(2) From the seleno analogues of the mercaptans; that is, from compoimds of the type RSeH, where R is an aliphatic group. The eompound RSeH, which may be termed a "seleno mercaptan, is converted to a metal seleno mercaptide, which is then condensed with a halogenated hydrocarbon, such as cetyl chloridefor also other selenium compounds. It has been found that when this mixture is heated with a halogenated hydrocarbon or mixture of hydrocarbons, such as lauryl chloride or chlorinated wax, the product, comprising a complex mixture of selenides and probably including monoand di-selenides, perhaps also higher polyselenides, is an excellent lubricant additive.

The following specific examples will serve to illustrate the practice and advantages of the invention.

Example 1-Lauson engine tests.The oils under test were used as crankcase lubricants of a single cylinder Lauson gasoline engine, the same type of engine as described in Farrington et al. United Statesv Patent'No. 2,325,597. The engine was operated at a speed of 1200 revolutions per minute, engine jacket temperature was maintained at 325 F., crankcase oil temperature was maintained at 300 F., and theengine was operated for 30 hour periods. The results are set forth in Table I below.

Table I .Lauson engine tests The base oil of Table Iwas an, SAE 30 blend of solvent treated California naphthenic base oil and a California parafilnic oil. Piston discoloration number, often referred to as PD No." dea halogenated mixture of hydrocarbons, such as chlorinated wax. This method is especially suited to the preparation of mixed selenides. such as cetyl ethyl selenide; for example, as follows:

wherein M is a metal such as an alkali metal.

(3) lDiselenides such as dilauryl diselenlde can be readily and economically prepared bythe following series of reactions:

method does not yield as desirable a product,-

from the standpoint of lubricant additives, when RX in Reaction b is chlorinated wax as it yields when RX is one of the lower, purer alkyl chlo-- rides, such as lauryl chloride or cetyl chloride. (4) Selenium is dissolved in strong aqueous or alcoholic caustic soda or caustic potash solution to yield a mixture (in solution) of alkali metal selenides, polyselenides and selenites, possibly notes a method of rating the performance of a lubricant. At the end of 30 hours and a ain atthe end of hours the engine is disassembled, the piston skirt is examined visually to determine PD No. and the parts are reassembled. The parts are cleaned before reassembly after the 60 hour run. A piston skirt which is completely black rates a PD No. of 800, one which is completely.clean rates a PD No. of zero, and piston skirts which are intermediate between completely black and completely clean are rated proportionately.

Example 2-Oa:idator tests-Samples of oil were subjected to an "oxidator test in an apparatus of the type described by Dornte in Industrial Engineering Chemistryfi vol. 28, page 26 (1936). In this test oxygen gas maintained at I atmospheric pressure is absorbed by the oil under test, the oil temperature being 340 F. Results are set forth in Table II below.

The thiocarbamates hereinabcve described may be used in oil in proportions of 0.1 per cent or less to 2 per cent or more, about 0.5 to 2 per cent being preferred, and the s'elenides may be used in oil in proportions of 0.1 per cent or less to 2 per cent or more, about 0.25 to 1.5 per cent being preferred. All percent ges so stated are by weight based on finished oil. Concentrates containing much larger proportions of thiocarbamate and selenide dispersed in hydrocarbon lubricating oil or the like may be prepared for later blending with more oil to produce the finished lubricant. For example, concentrates containing 5 to 50% of thiocarbamate and 5 to 50% selenide may be prepared, such percentages'being by weight based on total concentrate.

The compounding of the invention, comprising a thiocarbamate and a selenide, is most useful in crankcase oils, especially in heavy duty crankcase oils, but it may be used advantageously in other types of lubricant including greases and it may be used in insulating oils and the like.

Besides the ingredients indicated, the finished oils of the invention may contain other ingredients, such as extreme pressure agents, blooming agents, pour point inhibitors, etc.

Thi application is a continuation-in-part of our copending application Serial No. 506,726, filed October 18, 1943 now United States Patent No. 2,394,536, issued February 12, 1946, which in turn is a continuation-in-part of application Serial No.

- 432,040 (now issued as U. S. Patent No. 2,346,155)

$23 application Serial No. 486,306, filed May 10,

We claim:

1. A composition of matter comprising a major proportion of an oil of lubricating viscosity and a small amount each, not less than about 0.1% by weight based on said oil, of a salt of a thiocarbamic acid and an aliphatic selenide selected from the group consisting of aliphatic monoselenides and aliphatic polyselenides.

2. A composition of matter comprising a major a proportion of an oil of lubricating viscosity and a small amount each, not less than about 0.1% by weight based on said oil, or an oil-soluble polyvalent metal salt of a dithiocarbamic acid derivable from a secondary amine and an aliphatic selenide containing at least 8 carbon atoms, said aliphatic selenide being selected from the group consisting of aliphatic monoselenides and allphatic polyselenides.

3. The composition oi: claim 2, wherein said aliphatic selenide is a primary aliphatic monoselenide.

4. The composition of claim 2, wherein said aliphatic selenide is a polyselenide.

5. A lubricating composition comprising a, ma- :Ior proportion of a hydrocarbon lubricating oil and a small amount each, not less than about 0.1% by weight based on finished lubricant, of an oil-soluble polyvalent metal salt 0! a dithlocarbamic acid derivable from a secondary amine and a selenium compound having the formula wherein R1 and R2 are radicals each containing not less than 4 carbon atoms and selected from the group consisting of aliphatic, cyclo-aliphatic and aryl substituted aliphatic and cyclo-aliphatic radicals, Se is selenium and m is 1 or 2.

6. A petroleum lubricating oil comprising a major proportion of a petroleum oil of lubricating viscosity, about .1% to 2%by weight based on finished oil of an oil-soluble polyvalent metal salt of a dithiocarbamic acid derivable from a secondary amine and about .1% to 2% by weight based on finished oil of an aliphatic selenide containing at least 8 carbon atoms, said aliphatic selenide being selected from the group consisting of aliphatic monoselenides and aliphatic polyselenides.

'7. The oil of claim 6, wherein said polyvalent metal salt is the zinc salt of a dialkyl dithiocarbamic acid.

8. The oil of claim 6, wherein said polyvalent metal salt is a zinc reduced petroleum nitrogen base dithiocarbamate.

9. The oil of claim 6, wherein said polyvalent metal salt is the cadmium salt or a dialkyl dithiocarbamic acid.

10. The oil of claim 6, wherein said polyvalent metal salt is a cadmium reduced petroleum nitrogen base dithiocarbamate.

11. The oil of claim 6, wherein said aliphatic selenide is a primary aliphatic monoselenide containing not less than 4 carbon atoms in each aliphatic group.

12. The oil of claim 6, wherein said aliphatic selenide is diparaflln monoselenide.

13. The oil of claim 6, wherein said aliphatic selenide is dilauryl monoselenide.

14. The oil of claim 6, wherein said aliphatic selenide is dibenzyl monoselenide.

15. A'dispersion in hydrocarbon oil of lubricating viscosity of notI less than about 5 per cent of a salt of a thiocfl'bamic acid and not less than about 5 per cent of an aliphatic selenide selected from the group consisting of aliphatic monoselenides and aliphatic selenides, said percentages being by weight based on the dispersion.

GEORGE H. DENISON, JR. PAUL C. CONDIT. 

